Atherosclerotic cardiovascular disease is common, and is caused by a narrowing of the arterial lining due to atherosclerotic plaques. Medical balloons are used in the body in the treatment of atherosclerotic cardiovascular disease and include dilatation devices for compressing plaque and for expanding prosthetic devices such as stents at a desired location in a bodily vessel.
Percutaneous transluminal coronary angioplasty, or balloon angioplasty, is a non-invasive, non-surgical means of treating peripheral and coronary arteries. This technique consists of inserting an uninflated balloon catheter into the affected artery. Dilation of the diseased segment of artery is accomplished by inflating the balloon which pushes the atherosclerotic lesion outward, thereby enlarging the arterial diameter.
Another type of medical balloons are those having cutting edges, also referred to as atherotomes or blades, for recanalizing and dilating a diseased vessel, and facilitating balloon angioplasty procedures.
In either type of application, it is typically necessary for the balloon to traverse a tortuous anatomy as it is being delivered to the location in a bodily vessel; it is desirable for the balloon to assume as low a profile, i.e. the outer diameter of the distal end portion of the balloon, as possible. Considerable effort has been put forth in the development of dilatation balloons with a low profile by minimizing the dimensions of the core or the inner tube which extends through the balloon to its distal end, and by reducing the wall thickness of the balloon itself.
One way to achieve a low profile in the deflated state of the balloon is by folding the balloon to form a number of wings. In the deflated state, the balloon collapses upon itself forming flaps or wings that must be folded or wrapped around the balloon catheter to allow it to be withdrawn from the patient's vasculature after use.
Also prior to use, the balloon is typically folded or wrapped about the balloon catheter to fit within and pass through the guide catheter lumen. When inflation fluid is applied to the deflated balloon, the balloon wings or flaps unwrap and the balloon inflates to a fully expanded condition.
Various techniques or balloon constructions have been employed to facilitate the folding of the balloon about the balloon catheter in a uniform manner upon evacuation and deflation of the balloon after use.
One approach has been to construct the balloon of a cylinder of material, such as polyethylene, that is uniform about its circumference but can be heat set after it is wrapped or folded to form curved, overlapping flaps or wings extending from fold lines in a manner described further below. Heat setting of the balloon results in a balloon that when, upon application of negative pressure during deflation, will return fairly closely to its tightly wrapped heat set configuration.
Another approach has been taken to fabricate the balloon itself with fold line structures and flap shapes, particularly for use with balloons formed of stronger polyesters, for example, polyethylene terepthalate (PET).
There remains a need, however, for innovative and improved methods for folding balloons and for improved balloon refold.
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Without limiting the scope of the invention a brief summary of the claimed embodiments of the invention is set forth below. Additional details of the summarized embodiments of the invention and/or additional embodiments of the invention may be found in the Detailed Description of the Invention below.